unit of length equal to 1/100 of a metre

A centimetre (the American spelling is centimeter, symbol cm) is a unit of length in the International System of Units (SI) measurement system. It is equal to one hundredth of a metre. Centi- is placed in front to say 'a hundredth'. The centimeter is the base unit of length in the old centimeter-gram-second (CGS) system of units.

The centimetre is usually used to measure things that are too big for millimetre but too small for metres. A centimetre is close to the length of a fingernail.

Similarities to other units of length

A carpenters' ruler with centimetre markings

1 centimetre is equal to:

  • 10 millimetres
  • 0.01 metre (1 metre is equal to 100 centimetres)
  • about 0.393700787401575 inch (1 inch is equal to 2.54 centimetres) [1]

1 cubic centimetre is equal to 1 millilitre, under the SI system of units.

Uses of centimetre


The centimetre is also used:

  • sometimes, to measure how much rain has fallen into a rain gauge;[2]
  • for heights of people, especially athletes, in metric nations;
  • in maps, centimetres are used to change from map scale to real-world scale of landscapes (kilometres).

Unicode symbols


The centimetre has Unicode symbols so it can be written in Mandarin Chinese, Japanese and Korean characters. [3]

  • centimetre (㎝) - code 339D
  • square centimetre (㎠) - code 33A0
  • cubic centimetre (㎤) - code 33A4

They are placed into one character, and it is mostly used with East Asian fonts.


  1. Inch - from Eric Weisstein's World of Physics
  2. "Rain Measurement, Rain Gauge, Wireless Rain Gauge, Rain Gage, Rain Gauge Data". Weathershack.com.
  3. [1] CJK Compatibility excerpt from The Unicode Standard, Version 4.1.